Cells Flashcards
what is the plasma membrane
a semi permeable barrier between the cytoplasm and the external environment
how does the plasma membrane communicate
through receptors on the cell surface
what does the structure of the plasma membrane include
a lipid bilayer, cholesterol and proteins
what is involved in the lipid bilayer
phospholipids, which create a fluic mosaic
what is the structure of a phospholipid
a polar head and two non polar tails
what does cholestrol provide in the plasma membrane
it provides membrane integrity, prevents lysis
where is cholesterol found in the plasma membrane
it is embedded in the inner layer
what are proteins in the plasma membrane
these are gateways that allow certain molecules in and out
what is the hierarchy of cells in relation to the building blocks of life
cells
tissues
organs
organ systems
what underpins many disease processes
disturbances in cell function
what do all cell types possess
- cell membrane
- DNA
- cytoplasm
- ribosomes
what are the main elements of prokaryotic cells
- small
- relatively simple internal structure, with no internal membrane bound structures or organelles
- include bacteria and their close relatives
- no true nucleus
what are the main elements of eukaryotic cells
- larger
- more complex
- found in higher animals and plants
- nucleus
does the plasma retain most organically produced chemicals inside the cell
yes
how does the plasma membrane allow a few molecules to cross
- simple diffusion
- facilitated diffusion
- osmosis
- active transport
what is an example of cell membrane pathologies
haemoglobinopathies
describe haemoglobinopathies
- cause sickle cell anaemia and thalassaemia
- both hereditary and characterised by defects in haemoglobin
- alterations in the organisation of the lipid bilayer phospholipids leads to a decrease in red blood cell life span and also makes them less efficient at being replaced
what does an alteration in the organisation of the lipid bilayer phospholipidsin red blood cells lead to
a decrease in red blood cell life span
what are sickle cell anaemia and thalassaemi both characterised by
defects in haemoglobin
what is thalassaemia
this is the name for a group of inherited conditions that affect a substance in the blood called haemoglobin. people with thalassaemia produce either no or too little haemoglobin
what is sickle cell anaemia
a genetic disease where the red blood cells take up the shape of a crescent or a “sickle” whcih allows them to be more easily destroyed. this leads to a decrease in transportation of oxygen around the body, leading to anaemia.
haemoglobin A, or hbA is the primary haemoglobin that is affected in sickle cell anaemia, and is made up of two alpha globin and beta globin chains. the beta globin chains can end up misshapen due to a mutation in the beta globin gene and this is what leads to sickle cell anaemia.
in which cell types can you find a nucleus
eukaryotic only
what is the nucleus the location of
most of the different types of nucleic acid
where is DNA largely restricted to
the nucleus
what kind of structure does the nucleus have
a double membrane structure - known as the nucleur envelope. consists of an inner membrane and an outer membrane, with a space called the perinuclear space in between
where is RNA formed
in the nucleus
what is the nuclear envelope
the double membrane structure of the nuclear membrane
why does the nucleus have a nuclear envelope
it allows RNA and other chemicals to pass, but not DNA
where are ribosomes constructed
in the nucleolus
what is the nucleolus
the “brain” of the nucleus. a spherical structure found in the cell’s nucleus that has a primary function of producing and assembling the cell’s ribosomes
why are there pores on the nuclear envelope
to regulate the passage of molecules between the nucleus and the cytoplasm
what is the nuclear lamina
a dense fibrillar network inside the nucleus
provides mechanical support
regulates DNA replication and cell division
which cell types are ribosomes found in
both prokaryotic and eukaryotic cells
are ribosomes the same size in prokaryotic and eukaryotic cells
no, they are slightly larger in eukaryotic cells
what is the structure of a ribosome
they have a small and a larger subunit. during translation, the two subunits come together around the mRNA molecule, forming a complete ribosome
what is the main role of ribosomes
to facilitate protien translation
what is the difference between the large and the small subunit of ribosomes
small = mRNA binds and is decoded
large = where amino acids are added
what are the three sits on the larger subunits of ribosomes
P - peptidyl-tRNA binding site
E - exit site
A - aminoacyl tRNA binding site
what are the pathologies that can occur in ribosomes
ribosomopathies
describe ribosomopathies
- these were pathologies that originally were though to be fatal
- due to defects in ribosome synthesis
- links to Treacher Collins Syndrome
what is treacher collins syndrome
caused by ribosomopathies, characterised by abnormal craniofacial development
what is the endoplasmic reticulum
a mesh of interconnected membranes involved in protein synthesis and transport